How are nucleotides joined and what does it form?
- condensation reaction
- phosphate group on carbon 5 of the pentose sugar forms covalent bond with OH group of 3 carbon on the adjacent pentose sugar.
- phosphodiester bonds
- polymer called polynucleotide
How are phosphodiester bonds broken?
- hydrolysis
- release individual nucleotides
- water released
What do the phosphodiester bonds provide in a polynucleotide?
- a long, strong sugar phosphate ‘backbone’ with a base attached to each sugar
What are nucleic acids?
- large molecules in cell nuclei
- two types: RNA and DNA
- roles in storage and transfer of genetic information and the synthesis of polypeptides (proteins)
What elements do nucleic acids contain?
- carbon
- hydrogen
- oxygen
- nitrogen
- phosphorus
How are nucleic acids formed?
- large polymers formed from many nucleotides (monomers) linked together in a chain
What are individual nucleotides components?
- pentose sugar
- phosphate group
- nitrogenous base
What makes DNA’s sugar different from RNA’s?
- lacks one oxygen on carbon 2
How is DNA’s structure different from RNA’s?
- has T base instead of U
- sugar is deoxyribose
- double stranded
How is RNA’s structure different from DNA’s?
- has U base instead of T
- sugar is ribose
- smaller molecule
- single stranded
How are DNA’s and RNA’s structure the same?
- form polymers in the same way
- phosphodiester bonds
- linear molecules
- both have sugar, base and phosphate
- have A,C and G bases
What are pyrimidines and which bases are pyrimidines?
- smaller bases
- contain single carbon ring structures
- thymine and cytosine and uracil
What are purines and which bases are purines?
- larger bases
- contain double carbon ring structures
- adenine and guanine
How are the nitrogenous bases bonded together?
- hydrogen bonds
- A-T has 2 H bonds
- C-G has 3 H bonds
What does antiparallel mean?
- each strand has a phosphate group (5’) at one end and OH group (3’) at the the other end
- the two parallel strands of the double helix are arranged so they run in opposite directions
Why do pyrimidine bases always pair with purine bases
- maintains constant distance between DNA ‘backbones’ resulting in parallel polynucleotide chains
What is complementary base pairing?
- A and T always bond and C and G always bond
- means there’s always equal amounts of the bases that are paired
What is the method of extracting DNA?
- Grind sample in pestle and mortar
- mix sample with detergent
- add salt
- add protease enzymes
- add layer of ethanol on top of sample
- DNA seen as white strands, forming between layer of sample and alcohol. DNA can be picked up by ‘spooling’ it onto a glass rod.
What does grinding the sample in DNA extraction do?
- breaks down cell walls
What does mixing the sample with detergent do in DNA extraction do?
- breaks down cell membrane, releasing cell contents into solution
What does adding salt to the sample in DNA extraction do?
- breaks hydrogen bonds between DNA and water molecules
What does adding protease enzymes to the sample in DNA extraction do?
- breaks down proteins in DNA
What does adding ethanol to the sample in DNA extraction do?
- alcohol causes DNA to precipitate out of solution
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Water13
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Carbohydrates21
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Cells Structure27
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Testing for Carbohydrates12
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Types of Microscopes20
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Lipids and Proteins72
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Plasma Membrane21
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Transports across membrane19
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Nucleic Acids23
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DNA Replication and the Genetic Code19
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Protein Synthesis18
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ATP8
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The Cell Cycle49
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The organisation and specialisation of cells16
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Stem Cells26
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Enzymes47
